FIELD OF THE INVENTION
The present invention relates to a control apparatus for a restraint device in a motor vehicle.
Modern control apparatuses for restraint devices in motor vehicles, by using suitable sensors, detect not only whether a collision forceful enough that the restraint device should be triggered is occurring, but also whether a child seat has been placed on the front passenger seat. If a child seat on the front passenger seat is detected, then the inflation of an air bag for front-impact protection installed in front of the front passenger seat, or of an air bag for side-impact protection installed to the side of the front passenger seat, is either averted or sharply reduced. If an air bag disposed in the vicinity of a child seat is inflated without restriction, the child sitting in the child seat can possibly be injured severely. Numerous devices for detecting a child seat disposed on a vehicle seat have therefore already been proposed.
From Published, European Patent Disclosure EP 0 708 002 A1, corresponding to U.S. Pat. No. 5,618,056 which is hereby incorporated by reference, a control apparatus with a child seat detecting device is known what has one transmitting and one receiving antenna, each disposed in the vehicle seat. If a child seat equipped with a transponder/resonator is placed on a thus-prepared vehicle seat, then its presence is detected. The detection occurs via a transmitting antenna in which an exciter field is output that is picked up by the transponder, modified in a characteristic way, and transmitted back to the vehicle seat. The measurement field picked up by the receiving antenna is examined for the presence of the signal characteristic for the presence of the transponder. If a child seat disposed on the vehicle seat is detected, an impact-detecting control device that trips restraint devices is influenced in such a way that a signal for tripping the restraint device is blocked.
If the child seat is provided with two transponders and if the vehicle seat has two transmitting antennas and two receiving antennas, then from the mere detection of a child seat, the orientation of the child seat can be ascertained. A forward-facing child seat disposed on the vehicle seat can thus be distinguished from a rear-facing child seat on the vehicle seat, whose backrest thus faces the dashboard. Tripping of the restraint device can be varied depending on the orientation of the child seat. For instance, if a forward-facing child seat is detected, tripping can be allowed, while for a rear-facing child seat tripping is prevented.
Tripping of the restraint device is influenced by the known control apparatus solely as a function of the detection of a forward-facing or rear-facing child seat, and hence on the basis of only a few parameters. Under certain preconditions, tripping will therefore be prevented even when tripping would do more good than harm to the child in the child seat.
From U.S. Pat. No. 5,413,378, a control apparatus for a restraint device in a motor vehicle is known which has a weight sensor disposed in the vehicle seat. Various pickups (i.e. sensors) for vehicle seat settings, such as one pickup for the position of the vehicle seat and one pickup for the angle of inclination of the seat back, and ultrasonic sensors can also be used. Depending on the position of a passenger as detected by the sensors, the inflation of an air bag is done in metered fashion. For instance, if a passenger who is sitting far forward toward the dashboard is detected, the air bag is inflated only slightly, or in other words with a small volume of gas.